Planar, microstrip antennas have characteristics often sought for portable communication devices, including advantages in cost, efficiency, size, and weight. A planar antenna is typically formed by disposing a patch radiator on one side of a grounded dielectric substrate. So formed, the antenna is somewhat directional in that its radiation pattern is primarily directed outward from the patch radiator and away from the ground plane. However, some radiation inevitably spills around the ground plane in the opposite direction. This radiation flow is generally undesirable as the associated energy is often dissipated by absorptive materials that may be in close proximity. Such energy dissipation translates into a reduction of antenna efficiency.
Current trends demand a reduction in size, weight, and cost for portable communication devices. Smaller portable communication devices necessitates smaller antennas. Planar antennas show much promise in satisfying the need for antenna size, weight, and cost reduction. However, such smaller antennas are susceptible to efficiency losses from the close proximity of absorptive materials in and around the communication device. Accordingly, an improved design for antennas is needed.